1. Technical Field
Exemplary embodiments of the present invention relate to a failure recovery apparatus of digital logic circuit and method thereof when a fault occurs in the digital logic circuit.
2. Description of the Related Art
A CPU core means hardware or intellectual property (IP) which reads instructions stored in a storage such as a memory or a hard disk and executes an algorithm for a particular application, such as that executing a certain arithmetic operation to an operand according to operations encoded to the instructions and storing again the executed result.
Application range of the CPU core is extensive throughout the entire fields of system semiconductor. For example, application areas of the CPU core (processor core) have been extended from a high performance media data processing area for high performance multimedia data such as video/audio data compression and un-compression, audio data transformation and sound effects and a minimum performance microcontroller platform area such as modem for wire/wireless communication, voice codec algorithm, network data processing, touch screen, controller for home appliances, motor control and the like to device areas to which stable power supply or power supply from outside is impossible.
The CPU core is basically composed with a core, a translation lookaside buffer (TLB) and a cache. Operations to be performed by the CPU core are regulated with combination of a plurality of instructions. Instructions are stored in a memory and are inputted sequentially to the CPU core so that the CPU core can perform a particular operation every clock cycle. The TLB converts a virtual address to a physical address to perform operation system-based applications and the cache temporally stores the instructions, which are stored in an external memory, in an internal chip to increase speed of the CPU core.
In response to the development in driver assistance systems with a high level of intelligence and precision such as advanced drive assistance systems (ADAS) to the automate vehicle systems, importance of electronic systems has been increasing. Particularly, it is expected that applications using a CPU core having high performance of higher than 50 MHz-100 MHz, preferably 500 MHz or higher, may be significantly increased as a device to recognize external environments of a vehicle instead of a driver. Such applications may include motion detection of smart blackbox, pedestrian recognition during vehicle operation, driving assistance through driver's driving pattern or drowsiness recognition and lane detection. Thus, it must be able to analyze big data in real time using a CPU core having high performance to directly or indirectly involve in vehicle operation by recognizing external environments and analyzing the recognized video information, sound information and sensor information. Particularly, in case of lane detection-based driving assistance, the recognized result may have direct influence on a steering system and the like during vehicle operation. Vibrating a handle or restricting handle rotation angle or the like may be used to notify lane detection result to a driver as a method for providing direct influence to the steering system.
Reliability of the CPU core, which is a function to detect whether the CPU core operates normally or not, becomes more important for applications which recognize external environment data of a vehicle and have direct influence to the steering system of the vehicle. When any fault is caused in a semiconductor due to at least one factor of voltage, current and temperature, etc. under the condition that the recognized result directly affects the steering system of the vehicle, it may threat a driver's life. When such results of the CPU core affect the steering system, stability to ensure that the CPU core operates as it is intended may be very important.